1. Field of the Invention
This invention relates to the field of color inks and paints used in the printing, signage, fine and decorative arts industries.
2. Description of Related Art
David Makow in Color, Vol. 11, No. 3, p.205 (1986) has shown that cholesteric liquid crystals (CLC), and in particular, the CLC polymers (U.S. Pat. No. 4,410,570), possess color properties and effects that are not possible to obtain by conventional dyes and pigments, including: additive color properties; higher saturation and wider color gamut. However, in their present forms, liquid crystal coatings cannot be used as general purpose color inks and paints for the printing, signage, fine and decorative arts industries. CLC's in the liquid phase are not possible to use unless they are somehow encapsulated. The CLC polymer coatings, on the other hand, are solid at room temperature, and as Makow showed, produce remarkable color effects and are highly stable. These CLC polymers are still inconvenient for general purpose applications because they have to be applied at high temperatures. The polysiloxane-based CLC polymers are applied at 140.degree. C. in the liquid crystal phase and its molecules must be aligned to form the helical configuration with the helix axis perpendicular to the substrate (paper or canvas). This constrains the use of CLC polymers only in special applications and only by specialists.
This invention shows that by making CLC polymers into flat flakes or platelets having the helical axis normal to the platelets surface and mixing them in a suitable fluid, the prior art problems are solved, making it possible for CLC polymers to be conveniently used for general purpose applications exploiting their remarkable color properties. This is a CLC ink which is applied at room temperature, and no further alignment by the user is needed, since the platelets are already in the proper helical configuration.